A significant trend throughout integrated circuit (IC) development is the downsizing of IC components. As the size reduces, the performance requirements become more stringent. Also, as devices continue to shrink in size, the channel region continues to shrink as well. For metal-oxide-semiconductor field effect transistors (MOSFETs), increased performance requirements such as current and speed have generally been met by aggressively scaling the length of the channel region.
One technique that may improve scaling limits and device performance is to introduce strain into the channel region, which can improve electron and/or hole mobility. When applied in a longitudinal direction (i.e., in the direction of current flow), tensile stress is known to enhance electron mobility (n-type FET drive currents) while compressive stress is known to enhance hole mobility (p-type FET drive currents). The application of stresses to field effect transistors (FETs) is known to improve their performance.